Java Program to Find Power of Number

You can find the power of a number in Java by using a loop to multiply the base number by itself exponent times, for example: for (int i = 1; i <= exponent; i++) result *= base;.

Examples

Inputbase = 2, exponent = 3

Output8

Inputbase = 5, exponent = 0

Output1

Inputbase = 3, exponent = 4

Output81

How to Think About It

To find the power of a number, multiply the base number by itself repeatedly as many times as the exponent indicates. If the exponent is zero, the result is always 1. This approach uses simple repeated multiplication.

Algorithm

1

Get the base number and exponent as input.

2

Initialize a result variable to 1.

3

Repeat multiplying the result by the base number exponent times.

4

Return or print the result.

Code

java

public class PowerCalculator {
    public static void main(String[] args) {
        int base = 2;
        int exponent = 3;
        int result = 1;
        for (int i = 1; i <= exponent; i++) {
            result *= base;
        }
        System.out.println("Result: " + result);
    }
}

Output

Result: 8

Dry Run

Let's trace base=2 and exponent=3 through the code

1

Initialize variables

base=2, exponent=3, result=1

2

First loop iteration

result = 1 * 2 = 2

3

Second loop iteration

result = 2 * 2 = 4

4

Third loop iteration

result = 4 * 2 = 8

5

Loop ends

Final result = 8

Iteration	Result
1	2
2	4
3	8

Why This Works

Step 1: Start with result as 1

We set result = 1 because multiplying by 1 does not change the value and it is the neutral element for multiplication.

Step 2: Multiply result by base repeatedly

Each loop multiplies result by base, simulating the power operation by repeated multiplication.

Step 3: Return the final result

After the loop finishes, result holds the base raised to the exponent, which we print.

Alternative Approaches

Using Math.pow() method

java

public class PowerCalculator {
    public static void main(String[] args) {
        int base = 2;
        int exponent = 3;
        double result = Math.pow(base, exponent);
        System.out.println("Result: " + (int)result);
    }
}

This uses Java's built-in method for power, which is simpler and handles decimals but returns a double.

Using recursion

java

public class PowerCalculator {
    public static int power(int base, int exponent) {
        if (exponent == 0) return 1;
        return base * power(base, exponent - 1);
    }
    public static void main(String[] args) {
        int base = 2;
        int exponent = 3;
        System.out.println("Result: " + power(base, exponent));
    }
}

This uses a recursive function to calculate power, which is elegant but can cause stack overflow for large exponents.

Complexity: O(n) time, O(1) space

Time Complexity

The loop runs exponent times, so the time complexity is O(n) where n is the exponent.

Space Complexity

Only a few variables are used, so space complexity is O(1).

Which Approach is Fastest?

Using Math.pow() is fastest and optimized internally, while loops and recursion are straightforward but slower for large exponents.

Approach	Time	Space	Best For
Loop multiplication	O(n)	O(1)	Simple integer powers
Math.pow() method	O(1)	O(1)	All numeric powers, including decimals
Recursion	O(n)	O(n)	Elegant code, small exponents